HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

A New Ubiquitin-activating Enzyme

The addition of ubiquitin to proteins occurs through a multistep pathway. In the first step, UBE1 activates ubiquitin in an ATP-dependent manner. Ubiquitin is then transferred to the conjugating enzyme UBE2 and then to the protein ligase UBE3, which forms an isopeptide bond between ubiquitin and a lysine on the target protein. UBE1 is highly conserved in yeast, plants, and humans, and up until now, it has been assumed that only a single activating enzyme for ubiquitin exists.

UBE1L2 is expressed primarily in the testes.

In this Paper of the Week, Christiane Pelzer and colleagues identified a novel human ubiquitin-activating enzyme that they refer to as UBE1L2. The UBE1L2 sequence displays a 40% identity to UBE1 and also contains an ATP-binding domain and an active site cysteine that is conserved among E1 family proteins. UBE1L2 forms a covalent link with ubiquitin both in vitro and in vivo and is able to activate ubiquitin and transfer it to a ubiquitin-conjugating enzyme. Furthermore, ubiquitin activated by UBE1L2 can be used to ubiquitinate several different proteins. Because UBE1L2 is highly expressed in the testis, the authors speculate that the enzyme may serve an organ-specific function.

FOOTNOTES

See referenced article, J. Biol. Chem. 2007, 282, 23010-23014

[More Papers of the Week]